10 February 2016

Uranus

Before we begin, let’s get a few things out of the way. The noxious atmosphere around Uranus could kill a man. Uranus has a circumference of 100,000 miles. Scientists are looking at a black hole near Uranus. What are those two circular objects either side of Uranus? Ass-teroids, of course. If you got through that without laughing, then we’re good to go.

The discovery of Uranus (stop sniggering, you at the back) is credited to the German-born English astronomer William Herschel in 1781. Although it had been observed by scientists and astronomers for centuries, Uranus had always been mistaken for a star, and right up to Herschel’s discovery it was still being classed as 34 Tauri, a minor star in the constellation Taurus. Even Herschel himself initially believed he had spotted a comet rather than a planet, after noting that an object he had been looking at from his observatory in Bath had changed position in the sky over a series of nights.

Herschel announced his discovery in March 1781. As word of his new “comet” spread, astronomers all across Europe began to take note and observe it themselves. Soon, enough data had been compiled to plot its apparent trajectory—which, to everyone’s surprise, appeared to be an almost perfect circular orbit around the Sun. Herschel’s discovery was no comet.

Full colour photo of Uranus. Stop laughing.

By 1783, it had become universally acknowledged that Herschel’s discovery must surely be a planet—moreover, it was the first planet ever discovered by telescope, and the first new planet added to our Solar System in modern history. It was a truly monumental discovery, and one that earned Herschel an annual salary of £200 (equivalent to £27,000/$40,000 today) from King George III (on the condition that he move his observatory from Bath to Windsor, to be closer to the royal household), as well as the never-to-be-repeated title of Court Astronomer to The King.

But with the existence of a new planet confirmed, a pressing question soon emerged: what on Earth should it be called?

The Astronomer Royal, Nevil Maskelyne, wrote to Herschel asking him “to do the astronomical world the favour” and “give a name to your planet,” which, he continued, “is entirely your own, [and] which we are so much obliged to you for the discovery of.” In honour of his new financial patron, Herschel plumped for the only name he saw fit: Georgium Sidus, or “George’s Star.” He wrote to the Royal Society:

In the fabulous ages of ancient times the appellations of Mercury, Venus, Mars, Jupiter and Saturn were given to the Planets, as being the names of their principal heroes and divinities… The first consideration of any particular event, or remarkable incident, seems to be its chronology: if in any future age it should be asked, when this last-found Planet was discovered? It would be a very satisfactory answer to say, “In the reign of King George the Third”.

The seventh planet from the Sun, ultimately, was to be called George. But the response to Herschel’s suggestion was far from encouraging.

Outside of Europe, astronomers were wary of using a such an explicitly “British” name, especially given that it had taken an international collaboration to prove its status as a planet. Consequently, despite Maskelyne specifying that Herschel’s discovery and his choice of name were “entirely his own”, George failed to gain any widespread use or permanency. The name Georgium Sidus effectively became a placeholder, and over the years that followed astronomers across Europe began utilising and pitching their own choices and suggestions.

One popular choice was simply Herschel, a name honouring its discoverer. The Swedish astronomer Erik Prosperin ironically opted for Neptune (now the name of the eighth planet, discovered in 1846). But eventually a clear choice emerged—namely the German astronomer Johann Elert Bode’s suggestion, Uranus.

Bode had been one of the European astronomers who had calculated Uranus’ orbit, lending weight to the idea that Herschel’s discovery was a planet not a star. He suggested the name Uranus as it not only maintained the classical and mythological theme set out by the other six planets, but fittingly Uranus was the Greek god of the sky. Moreover, just as Saturn had been the father of Jupiter, Uranus was the father of Saturn, thereby creating a mythological family tree in the heavens.

Bose’s choice quickly gained momentum, and was reinforced by the German chemist Martin Klaproth in 1789, who named his famous discovery—the chemical element uranium—in support of Bose’s suggestion.

Out of deference to Herschel, however, it took another 60 years for the name Uranus to be universally acknowledged by the scientific community, when, in 1850, the official astronomical almanac published by the Royal Greenwich Observatory in London finally abandoned Herschel’s Georgium Sidus and in favour of Uranus.